Active Control of Cascade Flutter in High-speed Flows by Acoustic Excitation

点击翻译按钮获取中文摘要

New subsonic wind tunnel facility for active control of cascade flutter and particle image velocimetry (PIV) has been constructed. Using the system and numerical simulations, the following results are obtained.Active Control :・ Flutter frequency and critical velocity of a flat plate blade (139.5*50*1mm) are estimated 118 Hz and 143 m/s respectively from the flutter experiment. On the other hand, they are found to be 165Hz and 123m/s from a finite element method calculation. This is because the FEM calculation neglects the effect of separated flow on the surface of a blade vibrating.・ The optimum suppression conditions of the flutter are calculated as follows ;- The center of actuator is located at the center of chord in stream-wise direction,- The amplitude and phase difference are 0.14 and -54 degrees respectively, which are normalized by bending oscillation.・ Amplitude of blade vibration is decreased by the acoustic excitation from two actuator diaphragms on tip-side wall when the diaphragms are operated based on bending vibration of the blade.PIV :・ Uniform flow velocity vectors are measured with the PIV system.・ Velocity vectors of steady flow around biconvex blade are measured with the PIV system.・ Turbulent flow around cylinder at Reynolds Number 1.0x10^5 is visualized with the NV system, in particular K・rm・n vortices behind cylinder are periodically observed.